Cooked chicken breasts, shredded with a fork
Cheese, lettuce, tomato, black beans, avocado, whatever other toppings you like!
When split chicken breasts are on sale I stock up on them. In the morning Ill place 6-8 in a large pot and slowly simmer them most of the day. When they are good and tender I take them out with a slotted spoon and let them cool a few minutes. The meat should shred easily with a fork. Fill a skillet with as much meat as you need to feed your family. Actually make a little more, trust me the leftovers are awesome!
Add some of the seasoning mix and a little of the broth left in your cooking pot. Taste and see if it is enough, add as much as you like. If you like it really spicy you can add cayenne or other peppers. Let it simmer a bit till the liquid is absorbed.
Then place some on a warmed tortilla, or taco shell if you prefer. Add the toppings you like and you are done! Use the leftover chicken for other meals or freeze it for use later on.